Salem, Oregon is 30 degrees due west of St. Paul, Minnesota, the

latitude of both cities being 45◦ north of the equator. How far is it
(a)from Salem to the equator?
(b)from St. Paul to Salem, traveling due west along the circle of latitude?

3 answers

To solve this problem, we can use the concept of latitude and the distance between lines of longitude.

(a) From Salem to the equator:
Since both cities have the same latitude of 45 degrees north of the equator, the distance from Salem to the equator would be the same as the distance from St. Paul to the equator.

The equator is located at 0 degrees latitude, and since both cities are at 45 degrees latitude, the distance from Salem to the equator would be 45 degrees of latitude.

To calculate the distance in miles, we can use the fact that each degree of latitude is approximately 69 miles. Therefore, the distance from Salem to the equator would be 45 degrees * 69 miles/degree = 3,105 miles.

(b) From St. Paul to Salem, traveling due west along the circle of latitude:
To calculate the distance from St. Paul to Salem, traveling due west along the circle of latitude, we need to know the distance between lines of longitude at the latitude of 45 degrees north.

At the equator, the distance between lines of longitude is approximately 69 miles. However, as we move towards the poles, the distance between lines of longitude decreases.

To calculate the distance between lines of longitude at 45 degrees latitude, we can use the formula:

Distance between lines of longitude = (cos latitude) * (distance between lines of longitude at the equator)

Using trigonometric functions, the cosine of 45 degrees is 0.707. Therefore, the distance between lines of longitude at 45 degrees latitude is approximately 0.707 * 69 miles = 48.6 miles.

Since Salem is 30 degrees due west of St. Paul, we can calculate the distance by multiplying the number of degrees by the distance between lines of longitude:

Distance from St. Paul to Salem = 30 degrees * 48.6 miles/degree = 1,458 miles.
Salem, Oregon is 30 degrees due west of St. Paul, Minnesota, the
latitude of both cities being 45 degrees north of the equator. How far is it
(a)from Salem to the equator?
(b)from St. Paul to Salem, traveling due west along the circle of latitude?
The earths radius is 3960
To solve this problem, we need to calculate the length of the arc between the two cities.

(a) From Salem to the equator:
The distance from Salem to the equator can be calculated using the formula for the length of an arc on a sphere:

Arc length = (angle/360 degrees) * 2 * pi * radius

Since Salem is located 45 degrees north of the equator, the angle would be 45 degrees. Plugging in the values, we get:

Arc length = (45/360) * 2 * pi * 3960 miles = 495 miles

Therefore, the distance from Salem to the equator is approximately 495 miles.

(b) From St. Paul to Salem, traveling due west along the circle of latitude:
To calculate this distance, we need to find the circumference of the circle of latitude at 45 degrees north.

Circumference = 2 * pi * radius * (cos latitude)

Using the values provided, the circumference at 45 degrees north is:

Circumference = 2 * pi * 3960 miles * (cos 45) = 2 * pi * 3960 miles * 0.707 = 5564 miles

Since Salem is 30 degrees west of St. Paul, the distance between them along the circle of latitude would be:

Distance = (30/360) * 5564 miles = 463.67 miles

Therefore, the distance from St. Paul to Salem, traveling due west along the circle of latitude, is approximately 463.67 miles.